Upgrade your ship and fight waves of neon-colored shapes in this two-stick shooter.

Isotope takes the simple premise of a twin stick shooter–one virtual joystick on the left of the screen moves the ship, and another on the right fires in the direction pressed–and handles like a dream. These are some of the best virtual controls we’ve used on the touchscreen.

Isotope offers a couple of ways to customize these controls. We preferred keeping the joysticks in a fixed position at the bottom of the screen. By default they will center wherever you first press your thumbs. Accelerometer-based movement and other firing options are also available, but they don’t offer the precision you’ll need when things get hectic.

Inside Tron’s laser disco

With more than 20 types of enemies, Isotope is constantly throwing new challenges at you. For example, let’s say you’re being herded into a corner by a swarm of relentless enemy drones, and you’re looking for an escape. As you begin to blast your way westward, the dreaded blue enemy we call “laserbeam guy” streaks across the screen, leaving you trapped.

You see, “laserbeam guy” does nothing but fly from wall to wall, planting laser receptacles as he goes. Once planted, the receptacles link together and draw a laser from wall to wall, blocking your progress. Left unchecked, “laserbeam guy” can quickly turn an empty playing field into a labyrinth of death. With little time before the enemies overwhelm your corner, you have to hit your booster powerup, granting you temporary invulnerability as you rocket out of the trap and across the screen, safe for another few seconds.

It’s scenarios like this that make Isotope exciting, and the various powerups and enhancements you can apply to your ship add another level of strategy to the game. The booster powerup is one of many abilities that can be purchased with credits earned through Isotope’s campaign or survival modes.

Also available are modules that increase the weapon and shield statistics of your ship. Ships can also be improved by gaining experience and leveling up, similar to powering up a character in an RPG. Isotope offers a bunch of ships to buy, and the more expensive ones have higher level caps. You can even purchase companion ships called satellites. These little guys level up at their own pace and can fire alongside you, heal you or detonate bombs.

With so many ways to customize your ship, Isotope will keep you occupied for a long time. It took us more than 4.5 hours to purchase the most powerful ship in the game, level it up and beat the campaign mode. Campaign mode is made up of 30 short levels that offer unique layouts and challenges.

While the campaign is great, the real replay value lies in survival mode. Getting a high score in survival mode is always interesting because you can select one of nine different starting points, so a skilled player with a powerful ship won’t have to grind through ten minutes of underpowered enemies before things get interesting.

Ow, my eyes!

The presentation in Isotope really put the icing on the cake. The disco floor backgrounds change color depending on the enemies present and the gunfire coming from your ship, and the soundtrack perfectly suits the action onscreen. The enemies are bright and easy to distinguish from each other, and some offscreen enemies can be identified solely by the sounds they make, preparing you for what you might face in a few seconds. The framerate also stays pretty steady throughout.

But the game isn’t perfect, and the biggest problem seriously hampers its pick-up-and-play appeal. Once you power up your ship in Isotope, you’ll have about nine different slots open to equip dozens of potential powerups. Unfortunately, the game does not save your configuration after you quit, so if you want to boot up the game and drop into a quick round of survival you’ll have to re-equip everything all over again.

The online leaderboards are pretty barebones as well, only highlighting your numerical ranking while showing the top 20 scores worldwide. Finally, the camera feels a bit too zoomed in at times, and it doesn’t pan up, down, left or right until you get quite close to the edges of the screen. Sometimes this will cause you to crash right into a group of enemies offscreen you couldn’t see. The developer has already expressed a desire to fix this problem, so hopefully it will come in a future update, but as it stands it can be a little frustrating.

Despite its flaws, Isotope is one of the most polished and complete games available in the App Store. The controls are great, the graphics shine and it’s just downright fun to play. Don’t miss this one.

AppSpy takes a look at AG Drive in their latest video review. Giving it top marks and only dinging it for not having multiplayer. If you like “swooshy swoopy futuristic racers” this one might be the one.